Back in the day, people use to laugh at the powerglide. Now they are very popular on the race track. 2 speeds is all you need to get to the end of the track. I'd keep the powerglide.

The PG is popular on the track when the motor's power band is matched to the RPM range that the car will see. Fewer shifts make for less lost time. That does NOT make it a good street trans, however. Why would you want only a 1.76:1 first gear in a heavy car?